Alert Message with Yes/No

I need the "No" button to cancel the removal of the subform.

The Yes button works, here is my script:

_Subform1.removeInstance(Subform1.count
- 1);

// Prompt the user 

var nResponse =
xfa.host.messageBox("You are about to remove a program. \n\nDo you
want to continue?", "Removing a
program?", 2, 2) 

// Test the response: Yes = 4 

if (nResponse == 4)
{ 

}